L-DOPA is administered to neurological patients for a variety of diseases including parkinsonism. Reported side effects of L-DOPA therapy include: insomnia, depression, hypomania and paranoid reactions. In this research alterations in various animal behavior such as motor activity and avoidance responding will be studied after high acute and chronic doses of L-DOPA. The neurochemical mechanism of these behavioral changes induced by excessive brain DOPA concentrations will be studied in an attempt to understand the behavioral side effects of L-DOPA therapy in human disease. The effects of L-DOPA on dopamine, norepinephrine and serotonin in various brain areas will be measured. Drugs which are known to alter serotonin synthesis and receptor sensitivity will be used in attempts to block various effects of L-DOPA. BIBLIOGRAPHIC REFERENCES: Hruska, R.E., Thut, P.D., Huxtable, R.J. and Bressler, R. Suppression of Conditioned Drinking by Taurine and Related Compounds. Physiol. Biochem. & Behav. 3: 393-599, 1975. Hruska, R.E., Thut, P.D., Huxtable, R. and Bressler, R. The effect of taurine on central temperature regulation. Pharmacologist 17: 256, 1975.